This invention relates to electrophotographic marking machines, and more specifically to an apparatus and method for monitoring operating parameters of the marking machine.
In servicing and repairing electrophotographic (EP) marking machines, it has long been observed that the accurate analysis of the root cause of a functional failure or malfunction is critical in the successful implementation of the proper repair. Accurate and quick error analysis reduces the costs for troubleshooting itself as well as the costs for replacement parts. Any tools suited to the effective and accurate troubleshooting of malfunctions will ultimately yield higher customer satisfaction.
In addition, most consumables and components are replaced in accordance with manufacturer""s recommendation which is based on copy or page-count. The end-of-life for the component or consumable is thus inferred rather than measured. As the copy count does not accurately reflect power-up and power-downs of the machine as well as ambient operating conditions, maintenance based on copy or page counts is inherently unreliable.
Therefore, the need exists for monitoring the operating conditions of an electrophotographic marking machine, wherein the operating parameters correspond to actual usage of the machine. The need also exists for permitting error analysis and trend analysis.
The present invention provides a system for retaining image generation parameters and operating set points in an electrophotographic marking machine. These stored parameters can be compared to EP setpoints together with other key operating parameters as function of copy-count to allow for the evaluation of the component or consumable health. Furthermore, the measured data allow the prediction of the end-of-life point based on customer specific operating conditions such as jobstream, toner throughput, environmental conditions and others which have been known to affect the useful life of consumables and components.
With measured data available as consumables or components age with printing (e.g. developer, photoconductor), the prediction of end-of-life allows the pro-active exchange of identified consumables and components and, thus, avoids a service call before the component or consumable fails. A service call placed by the customer due to end-of-life of consumables and/or components is likely avoided, thus increasing the customer perceived reliability and customer satisfaction.
In the present invention, a logic and control unit (LCU), or a marking engine controller (MEC) cooperates with the storage of short term and long term data corresponding to different aspects of the electrophotographic process. One aspect of the invention is incorporated into embedded software to allow one to separate the trouble shooting of marking engine failures or malfunctions from the assessment of long term drifts in machine performance, both of which are important in monitoring marking engine performance.
The software is integrated with the LCU and provides for on an on-line data recording of predetermined parameters. The predetermined EP-parameters are recorded and stored for later retrieval. Two segments of memory are reserved for selected machine parameters recorded in response to electrophotographic marking for, first, short-term error analysis (for EP-history recording) and, secondly, for machine set points in response to autosetups to allow long-term trend analysis (for EP-trend recording).
The invention provides for the measurement and storage of two data sets. For short-term analysis, data corresponding to machine conditions during or associated with electrophotographic marking are gathered. In a first configuration, the data associated with the electrophotographic marking are collected at a high frequency, typically each time an electrophotographic marking is made. For long-term trend analysis, data corresponding to machine set points are gathered less frequently, typically each time an autosetup is performed. Typically, autosetup occurs each time the marking engine is powered up, and additionally at preset intervals, such as six-hour intervals, during periods of continuous operation. The autosetup can also be executed by a field engineer during a service call. While long-term data would be accessible from high-frequency measurements performed over a sufficiently long time, they would have to be extracted from a large excess of data points. With this invention, long-term trends would be observable from a manageable number of data points, while short-term errors could still be conveniently observed from high-frequency measurements. Also, since all but the most recent data are redundant, the older data can be discarded on a first-in, first-out (FIFO) basis. In practice, the last 1000 high-frequency and the last 500 low-frequency data are retained. Therefore, the high frequency data provide a record of the last 1000 frames, while the low-frequency data would typically provide a record of about the last 200 workdays. Discarding older data than necessary minimizes the demands on software and memory.